Artificial crystalline lenses are often implanted in the eye to replace a crystalline lens which has been extracted via cataract surgery. In a modern cataract surgery and the accompanying implantation of an artificial crystalline lens, the most important matter of concern is that the surgery be minimally invasive. Making the incision in the eyeball tissue smaller is expected to have the effect of alleviating postoperative astigmatism, and making the incision smaller as well as reducing the surgery time are expected to reduce the occurrence of postoperative inflammation. Specifically, making a smaller incision in the eyeball tissue and reducing the time of a series of surgeries has the merits of promoting faster post-op eyesight recovery and alleviating the burdens imposed by surgery on both the patient and the surgeon.
Phacoemulsification is often used in modern cataract surgery, and it is possible to leave the crystalline lens capsule while extracting an opacified crystalline lens nucleus through an incision of about 2.8 mm in the eyeball tissue.
An artificial intraocular lens implanted in place of the extracted crystalline lens is implanted in the remaining crystalline lens capsule. Following the invention of foldable intraocular lenses, it has even been possible to insert an intraocular lens having an optical diameter of 6 mm into an incision of about 4 mm in the eyeball tissue by folding the lens in half. Furthermore, to insert an artificial intraocular lens into the eye through a small incision, a method has recently been proposed wherein the intraocular lens is folded and stored in a storage cartridge, and is pressed in and implanted with a plunger. It is possible to implant an artificial intraocular lens into the eye without widening the incision made in the eyeball tissue for phacoemulsification purposes.
One example of a specific method for implanting the artificial intraocular lens into the eyeball by using a cartridge and a plunger is an intraocular lens insertion system (see Japanese Publication No. 8-505540, for example) configured from a plunger, a cartridge, and a hand piece as a cylindrical main body. This intraocular lens insertion system has a lens compartment in the cartridge, and the intraocular lens placed in the lens compartment can be folded over by closing the lens compartment. After the lens is folded, the cartridge is mounted on the hand piece and the plunger is pressed in, whereby the intraocular lens can be implanted into the eye.
Since the distal end of the plunger has a unique bifurcated shape, the supporting part of the intraocular lens can be prevented from being crushed between and damaged by the inner wall of the cartridge and the distal end of the plunger when the intraocular lens is passed through the cartridge interior. Also, after the intraocular lens is inserted into the eye, the distal end of the bifurcated plunger can be used to adjust the position of the intraocular lens to a specific position.